Designation: C760 − 90 (Reapproved 2015)

Standard Test Methods for

Chemical and Spectrochemical Analysis of Nuclear-Grade
Silver-Indium-Cadmium Alloys1
This standard is issued under the fixed designation C760; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.

1. Scope

2.2 Other Document:
NBS Circular 6024

1.1 These test methods cover procedures for the chemical
and spectrochemical analysis of nuclear grade silver-indiumcadmium (Ag-In-Cd) alloys to determine compliance with
specifications.

3. Significance and Use
3.1 Silver-indium-cadmium alloy is used as a control material in nuclear reactors. In order to be suitable for this purpose,
the material must meet the specifications for assay and impurity content. These test methods are designed to show whether
or not a given material meets the specifications as given in
Specification C752.
3.1.1 An assay is performed to determine whether the
material has the chemical composition specified.
3.1.2 The impurity content is determined to ensure that the
maximum concentration limit of impurities is not exceeded.

1.2 The analytical procedures appear in the following order:
Silver, Indium, and Cadmium by a Titration Method

Trace Impurities by Carrier-Distillation Spectrochemical Method

Sections
7 – 15
16 – 22

1.3 The values stated in SI units are to be regarded as the
standard.
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard
and precautionary statements, see Section 5 and Practices E50.

4. Purity of Reagents
4.1 Reagent grade chemicals shall be used in all tests.
Unless otherwise indicated, it is intended that all reagents shall
conform to the specifications of the Committee on Analytical
Reagents of the American Chemical Society,5 where such
specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently
high purity to permit its use without lessening the accuracy of
the determination.

2. Referenced Documents
2.1 ASTM Standards:2
C752 Specification for Nuclear-Grade Silver-IndiumCadmium Alloy
D1193 Specification for Reagent Water
E50 Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and
Related Materials
E115 Practice for Photographic Processing in Optical Emission Spectrographic Analysis (Withdrawn 2002)3


4.2 Purity of Water—Unless otherwise indicated, references
to water shall be understood to mean reagent water conforming
to Specification D1193.
5. Hazards
5.1 Proper precautions should be taken to prevent inhalation
or ingestion of heavy element (silver, indium, or cadmium)
powder or dust during handling.
5.2 Workers should observe precautions as specified in
vendor-supplied Material Safety Data Sheets (MSDS).

1
These test methods are under the jurisdiction of ASTM Committee C26 on
Nuclear Fuel Cycle and are the direct responsibility of Subcommittee C26.03 on
Neutron Absorber Materials Specifications.
Current edition approved Jan. 1, 2015. Published January 2015. Originally
approved in 1971. Last previous edition approved in 2007 as C760 – 90 (2007).
DOI: 10.1520/C0760-90R15.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3
The last approved version of this historical standard is referenced on
www.astm.org.

4
Available from National Institute of Standards and Technology (NIST), 100
Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, .
5

Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K. and the United States Pharmacopeia and
National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States

1


C760 − 90 (2015)
EDTA into a small plastic beaker. Dissolve with water, transfer
quantitatively to a 1-L volumetric flask, and make up to volume
with water. Transfer the solution to a plastic storage bottle. Do
not allow the EDTA solution to stand in contact with glass
containers.

6. Sampling
6.1 Suggestions for sampling this alloy are given in Specification C752.
SILVER, INDIUM, AND CADMIUM BY A TITRATION
METHOD

11.5 Indium (In)—Metal, >99.99 % pure.
11.6 Nitric Acid (sp gr 1.42)—Concentrated nitric acid
(HNO3).

7. Scope
7.1 This test method is applicable to the determination of
silver, indium, and cadmium in alloys of approximately 80 %

silver, 15 % indium, and 5 % cadmium used in nuclear reactor
control rod applications. The titrimetric methods presented6,7
will yield results with a bias of the order of 0.1 %.

11.7 PAN Indicator Solution (0.1 % PAN in Methanol)—
Dissolve 100 mg of 1-(2-pyridylazo)-2-naphthol in 100 mL of
methyl alcohol and mix until completely dissolved.
11.8 Silver (Ag)—Metal, >99.99 % pure.
11.9 Sodium Chloride (NaCl).

8. Summary of Test Method

11.10 Sodium Chloride Solution (0.0500 M)—Dry sodium
chloride (NaCl) at 120°C, in a weighing bottle, to a constant
weight and cool to room temperature in a desiccator. Weigh
2.922 6 0.001 g of the dried NaCl into a small plastic beaker.
Dissolve in water, quantitatively transfer to a 1-L volumetric
flask, and make up to volume with water.

8.1 A weighed sample is dissolved in nitric acid and diluted
to a known volume, and aliquots are removed for analysis.
Silver is determined first by titrating with standardized sodium
chloride solution to the potentiometric endpoint indicated by a
chloride-selective ion electrode. Following the silver titration,
the solution is boiled to coagulate the silver chloride. The pH
is adjusted to 2.5 and the indium content is titrated with EDTA,
using PAN (1-(2-pyridylazo)-2-naphthol) indicator. The pH is
then raised to 6.0 and the cadmium is titrated with EDTA using
the same indicator. The entire process requires approximately
20 min per aliquot, exclusive of sample weighing and dissolution.


12. Standardization
12.1 Silver-Indium-Cadmium Calibration Standard:
12.1.1 Clean approximately 8.0 g of silver metal, 1.5 g of
indium metal, and 0.5 g of cadmium metal with an organic
solvent and air dry.
12.1.2 Weigh each metal accurately and transfer to a
100-mL beaker.
12.1.3 Add sufficient water to cover the metal pieces and
add HNO3 (sp gr 1.42) dropwise until dissolution is complete.
12.1.4 Transfer quantitatively to a 100-mL volumetric flask
and dilute to volume with water.

9. Interferences
9.1 No interferences have been observed from any elements
normally encountered as impurities in nuclear grade silverindium-cadmium alloy over the concentration ranges expected.
10. Apparatus

12.2 Calibration of NaCl and EDTA Titrants:
12.2.1 Pipet 10 mL of the calibration standard into a
100-mL volumetric flask and dilute to volume with water.
(Retain this solution as a working standard.)
12.2.2 Pipet 10 mL of the diluted standard into a 100-mL
beaker and adjust the volume to about 25 mL with water.
12.2.3 Adjust the pH to approximately 1 using NH4OH (sp
gr 0.90).
12.2.4 Place a TFE-fluorocarbon-coated stirring bar in the
solution and insert the chloride specific ion electrode and the
reference electrode.
12.2.5 Stir at a moderate rate and titrate the silver with NaCl

solution. Record millivolt readings versus volume added.
Allow sufficient time for equilibrium readings to be attained.
12.2.6 The titration end point is taken as the termination of
the rapidly rising segment of the millivolt versus volume
titration curve.
12.2.7 Adjust to pH 2.5 6 0.2 by dropwise addition of
acetate buffer solution (pH4).
12.2.8 Remove the electrodes and rinse thoroughly to avoid
loss of indium and cadmium.
12.2.9 Heat the solution to boiling on a hotplate until the
supernatant liquid is clear. Allow to cool.
12.2.10 Add 4 drops of PAN indicator solution. The solution
should be deep purple.

10.1 Burets, precision, two, 25-mL capacity, preferably
Schellbach type with TFE-fluorocarbon stopcock and automatic zero. They shall be certified or tested to conform with
tolerances specified in NBS Circular 602.
10.2 Reference Electrode—Saturated calomel electrode.
10.3 Glass pH Electrode—Standard type.
10.4 Chloride Specific Ion Electrode.
10.5 Expanded Scale pH/millivolt Meter.
11. Reagents
11.1 Ammonium Hydroxide (sp gr 0.90)—Concentrated ammonium hydroxide (NH4OH).
11.2 Buffer Solution, pH4—0.5 M sodium acetate—0.5 M
acetic acid.
11.3 Cadmium (Cd)—Metal, >99.99 % pure.
11.4 Ethylenediaminetetraacetate Dihydrate Disodium Salt
(EDTA) Solution (0.01000 M)—Weigh 3.722 6 0.001 g of
6
Cheng, K. L., “Complexometric Titration of Indium,” Analytical Chemistry,

Vol 27, 1955, p. 1582.
7
Cheng, K. L., “Complexometric Titration of Copper and Other Metals in a
Mixture,” Analytical Chemistry, Vol 30, 1958, p. 243.

2


C760 − 90 (2015)
TRACE IMPURITIES BY
CARRIER–DISTILLATION
SPECTROCHEMICAL METHOD

12.2.11 Titrate the indium with standard EDTA solution to
the sharp transition from purple to yellow. The volume used
corresponds to the indium content.
12.2.12 Adjust to pH 6 6 0.2 with NH4OH (sp gr 0.90). The
color of the solution will change back to purple.
12.2.13 Titrate the purple solution with standard EDTA until
the color again changes to yellow. The volume used corresponds to the cadmium content.

16.1 This test method is applicable to the determination of
the trace impurities listed in 19.1 in silver-indium-cadmium
alloys.

13. Procedure

17. Summary of Test Method

13.1 Clean approximately 1.0 g of the sample with an

organic solvent and air dry.

17.1 The sample is cleaned, and a weighed quantity is
dissolved in nitric acid. An equivalent weight of graphite is
added to the solution and it is evaporated to dryness at 85 6
5°C. The residue is moistened with a few drops of water and
mixed until a slurry is obtained. A dilute hydrochloric acid
solution is added and mixed well. The slurry is evaporated to
dryness at 85 6 5°C in subdued light.

16. Scope

13.2 Weigh the cleaned sample accurately and transfer it to
a 100-mL beaker.
13.3 Cover the sample with water and add HNO3 (sp gr
1.42) dropwise until the sample is completely dissolved.
13.4 Transfer the solution quantitatively to a 100-mL volumetric flask and dilute to volume with water.

17.2 The dried sample mixture is blended with a barium
fluoride-graphite carrier, weighed into graphite anode caps, and
excited in a d-c arc. The spectrum is recorded photographically,
and the spectral lines of interest are compared visually with
standards exposed on the same plate.

13.5 Proceed with the determination of silver, indium, and
cadmium as described in 12.2.2 – 12.2.13.
14. Calculation

18. Apparatus


14.1 Symbols:
S
D.F.
FS
FI
FC

=
=
=
=
=

18.1 Spectrograph—A spectrograph with sufficient resolving power and linear dispersion to separate the analytical lines
from other lines in the spectrum of the sample in the spectral
region from 220 to 400 nm is recommended. Instruments with
a reciprocal linear dispersion of 0.3 nm/mm or less are
satisfactory.

sample weight, mg,
dilution factor = 0.1,
calibration factor for silver, mg Ag/mL of titrant,
calibration factor for indium, mg In/mL of titrant, and
calibration factor for cadmium, mg Cd/mL of titrant.

18.2 Excitation Source—A d-c arc source capable of sustaining a 12-A d-c arc.

14.2 Calibration Calculations:
FS 5


mg of Ag in calibration standard aliquot
mL of standard NaCI solution added

(1)

18.3 Excitation Stand—Conventional type with adjustable
water-cooled electrode holders.

FI 5

mg of In in calibration standard aliquot
mL of standard EDTA solution added

(2)

18.4 Balance—A torsion-type balance with a capacity of 1.0
g and capable of weighing to the nearest 0.5 mg.

FC 5

mg of Cd in calibration standard aliquot
mL of standard EDTA solution added

(3)

18.5 Pulverizer-Mixer—A mechanical mixer with a plastic
vial and ball.

14.3 Sample Calculations:


18.6 Comparator—Conventional type is satisfactory.

Ag, % 5 mL of NaCl titrant 3 F S 3 10/S

(4)

In, % 5 mL of EDTA titrant 3 F I 3 10/S

(5)

Cd, % 5 mL of EDTA titrant 3 F C 3 10/S

(6)

18.7 Photographic Processing Equipment—Photographic
processing equipment conforming to the requirements of
Practices E115.
18.8 Steam Bath—Conventional type.

15. Precision and Bias

18.9 Drying Oven—Conventional type, stainless steel construction.

15.1 Precision—The estimated standard deviation for a
single measurement of each element is 0.03 % for silver,
indium, and cadmium.

18.10 Beakers—25 or 50-mL capacity TFE-fluorocarbon
construction.


15.2 Bias—The estimated bias, measured using a known
80 % Ag-15 % In-5 % Cd alloy, is as follows: Ag, − 0.02 %;
In, +0.09 %; Cd, −0.03 %, absolute.

18.11 Stirring Rods—TFE-fluorocarbon construction.
18.12 Venting Tool—See Fig. 1.

3


C760 − 90 (2015)
19.7 Nitric Acid (8 N)—Dilute 500 mL of redistilled nitric
acid (HNO3, sp gr 1.42) to 1 L with double-distilled water.
19.8 Silver—Silver metal, >99.99 % purity.
20. Procedure
20.1 Preparation of Standards:
20.1.1 A minimum of four standards containing 1 to 1000
µg/g of each impurity element to be determined by blending
known amounts of each impurity oxide or salt with a graphite
matrix.8
20.1.2 Dissolve 20.00 g of silver metal, 3.75 g of indium
metal, and 1.25 g of cadmium metal in 75-mL of 8 N HNO3.
Cool and dilute to 200-mL in a volumetric flask with doubledistilled water.
20.1.3 Pipet 2 mL of the Ag-In-Cd solution (see 20.1.2) into
each of five TFE-fluorocarbon beakers (25-mL capacity).
Weigh 250 6 1 mg of graphite into the first beaker and 250 6
1 mg of each graphite base standard (see 20.1.1) into the four
remaining beakers, one standard in each of the beakers.
20.1.4 Thoroughly mix the graphite and the solution using a
TFE-fluorocarbon stirring rod and carry through the sample

preparation procedure starting with 20.2.5.

in.
0.001
0.002
0.017
0.024
0.050
0.113
0.130

Metric Equivalents
mm
in.
0.03
0.05
0.43
0.61
1.27
2.87
3.30

0.154
0.200
0.330
3⁄32
1⁄ 4
5

20.2 Preparation of Samples:

20.2.1 Clean 0.5 to 1.0 g of sample with file, wash with
organic solvent, and air dry.
20.2.2 Weigh the sample to the nearest 1 mg and transfer it
to a 25-mL TFE-fluorocarbon beaker.
20.2.3 Add 5 mL of 8 N HNO3 and let stand until the sample
is completely dissolved.
20.2.4 Weigh an amount of graphite equivalent to the
sample weight 6 1.0 mg and transfer it to the TFEfluorocarbon beaker. Thoroughly mix using a TFEfluorocarbon stirring rod.
20.2.5 Evaporate to dryness on a steam bath.
20.2.6 Cool the sample and add about 1 mL of doubledistilled water and mix to a slurry with the TFE-fluorocarbon
rod.
20.2.7 Add 3 mL of 6 N HCl and mix thoroughly with the
TFE-fluorocarbon rod.
20.2.8 Evaporate to dryness in subdued light, or total
darkness, on the steam bath.
20.2.9 Place the beaker in a drying oven, in total darkness,
at 85 6 5°C for 3 h.
20.2.10 Cool and pulverize the sample, in the TFEfluorocarbon beaker, using the TFE-fluorocarbon stirring rod.
20.2.11 Use a mechanical mixer to blend 100 mg of sample
with 100 mg of BaF2-graphite carrier in a plastic vial with a
plastic ball for 30 s.

mm
3.91
5.08
8.38
2.4
6.4
127


FIG. 1 Venting Tool

18.13 Electrodes—ASTM Types S-1, S-2, and C-1.
19. Reagents
19.1 Barium Fluoride— (BaF2)—>99.90 % purity, < 10 µm
particle size.
19.2 Barium Fluoride-Graphite Carrier—Homogenize 5
parts BaF2 with 95 parts graphite in a plastic vial with a plastic
ball on a mechanical mixer.

NOTE 1—The actual carrier is the mixture of BaF2 and AgCl. The
BaF2-graphite is not sufficient if the silver in the sample is not converted
to AgCl.

19.3 Cadmium—Cadmium metal, >99.99 % purity.

20.2.12 Weigh duplicate 50-mg charges of samples and
standards into ASTM Type S-2 anode caps.
20.2.13 Tap pack, vent the charge, and electrically excite
under conditions listed below.

19.4 Graphite—Spectrographic grade, 200-mesh, nonpelletizing type.
19.5 Hydrochloric Acid (6 N)—Dilute 500-mL of redistilled
hydrochloric acid (HCl, sp gr 1.19) to 1 L with double-distilled
water.

8
G-Standards, commercially available from Spex Industries Inc., 3880 Park
Ave., Edison, NJ 08820, have been found satisfactory.


19.6 Indium—Indium metal, >99.99 % purity.
4


C760 − 90 (2015)
20.3 Spectrographic Procedure—Excitation and exposure
conditions:
Discharge
Current, A
Electrode gap, mm
Preburn, s
Exposure, s
Slit width, µm
Wavelength range, nm
Light transmission:
Total filter
Split field filter
Emulsion

Boron
Beryllium
Bismuth
Calcium
Cobalt
Chromium
Copper
Iron
Magnesium
Manganese
Molybdenum

Sodium
Nickel
Phosphorus
Lead
Silicon
Tin
Titanium
Vanadium
Zinc
Zirconium

d-c arc
10 (shorted)
3
5
40
10
210 to 440, first order
25 % T
100/10 % T
SA #1

20.4 Photographic Processing—Process the plates in accordance with Practice E115.
21. Calculation
21.1 Visually compare the density of the sample impurity
spectral line with the corresponding line in the standard
spectrum. Estimate the impurity concentration using the lines
listed in the following table.

Aluminum

Arsenic

Wavelength, nm
256.80, 308.22
309.27
234.98

249.77

422.67
304.40
327.40
302.06
280.27
280.11
313.26
300.25
261.42
251.43
317.50
322.35
318.40
330.26
334.82

1
1
1
50
1

10
1
10
10
10
10
50
10
100
5
10
5
10
5
10
100

to
to
to
to
to
to
to
to
to
to
to
to
to

to
to
to
to
to
to
to
to

100
100
100
1000
100
1000
100
1000
500
500
500
500
500
1000
100
500
100
500
100
500
1000


22. Precision and Bias
22.1 Precision—When the sample plates are visually compared to the standard plates, experienced analysts can expect
analytical results to vary within a factor of two; that is, 50 % to
200 % of the actual impurity element concentration.
22.2 Bias—Since there is no accepted reference material for
determining bias in this test method, no statement on bias is
being made.

Analytical Lines
Element

249.68,
234.86
306.77
393.37,
240.72,
283.56
324.75,
283.56,
279.55,
279.83,
317.04,
330.23
305.08,
255.33
283.31,
251.61,
284.00,
334.90,

318.34,
334.50,
339.20,

Concentration
Range, µg/g
10 to 500
50 to 500

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